Production of polar-substituted organic peroxides and products thereof



Patented May 16, 1950 UNITED STATES PATENT OFFICE 3 fi'rnaanor Berkeley,Cali! assig'nor to Shell Development Company, San Francisco,

Call! a corporation of Delaware No Drawing. Application December s,1948, Serial No. 63,851 a 9 Claims. (c1. 260465.1)

' diificult to obtain by other methods of synthesis.

Thisapplication is a continuation-in-part of my copending applicationSerial No. 762,809, filed July 22, 1947, now abandoned.

Hydroperoxides have recently become known and may be produced in variousways. For instance, U. S. Patent No. 2,395,523, issued February 26,1946, of Vaughan and Rust describes how such products may be made by thecontrolled oxidation in the presence or hydrogen bromide of branchedchain organic compounds which contain a tertiary carbon atom. Thus onemay oxidize isobutane and obtain tertiary-butyl hydroperoxide as well asother products. According to another method of producing such compounds,a tertiary alcohol, such as tertiary-butyl alcohol, is added to hydrogenperoxide in the presence of a dehydrating agent such as anhydrous sodiumsulfate to cause the formation of the hydroperoxide. Another methodconsists of reacting a mono-alkyl-salt of an inorganic acid withhydrogen peroxide and neutralizing the product to produce thecorresponding hydroperoxide.

Hydroperoxides are compounds of the formula RA-O-O-l-I in which R is anon-acyl radical. In their properties as well as in their structure theyare closely analogous to hydrogen peroxide. They are well knownoxidizing agents and initiators of polymerization reactions and thereactions heretofore known, between hydroperoxides and unsaturatedorganic compounds, have been of the type involving the decomposition ofthe hydroperoxides and the oxidation or polymerization or theunsaturated compounds.

I have now surprisingly discovered that hydroperoxides can be caused toenter into a reaction with an unsaturated compound of the class definedbelow, which reaction does not involve either polymerization oroxidation'of the unsaturated compound or the decomposition of thehydroperoxide. When a hydroperoxide, an unsaturated organic compound ofthe defined class and an alkaline-reacting compound are brought togetherin the same liquid phase so that the phase is kept alkaline but does notcontain enough base to convert substantially all of the hydroperoxide toa salt, the hydroperoxide molecules add to and saturate doubly-boundcarbon atoms of the unsaturated compound.

The unsaturated compounds which enter into this unique reaction arepolar compounds con-" taming at least one olefinic double bond not in aconjugate relation with other carbon-to-carbon multiple bonds andcontaining, attached to one of the carbon atoms joined by such a bond, apolar group which is a meta-directing? group. The term meta-directing"group is employed throughout the specification and claims to-refer tothe substituent groups which when they are 'the sole substituentattached to the ring of benzene direct the entrance of a secondsubstituent predominantly to the meta position. Numerous meta-directinggroups are well known to those skilled in the art, including the CH0,COOH, C0O(alkyl), 000(metal), CN, CCla, N02, SOsH, S02, CONHa, COCOOHand the like groups which are commonly so designated in the standardchemical texts. In any case, the existence of meta-directing propertiesis a readily determinable property of any group in question. It will berecognized by'those skilled in the art that,

as the reaction is conducted in an alkaline medium, acidic groups. suchas the carboxyl group, are best neutralized prior to employment in theprocess. 'I have found the presence of a metadirecting group in whichthe attaching atom is an unsaturated atom (particularly, the CN,COO(alkyl), COO(meta1) N02 and C0(alkyl) groups) renders the compoundparticularly suitable ior employment in the process of the invention.

Illustrative examples of oleflnic compounds (of which the aliphaticmonoolefinic compounds are preferred) containing a meta-directing groupattached to a, carbon atom joined by an olefinic double bond that reactsin accordance with the process of the invention include nitriles such ascrotononitrile, 2l4-pentadienenitrile and 2-octenenitrile; acids (whichare best employed as their alkali metal salts) such as acrylic,isohydrosorbic and crotonic; esters such as phenyl acrylate, propylcrotonate and butyl isohydrosorbate; nitro compounds such asl-nitro-l-propene, l-nitro-2-cyclohexylethylene, and l-nitrol-eicosene;aldehydes such as acrolein, methacrolein and isohydrosorbyl aldehyde;ketones such as methyl vinyl ketone, vinyl carboxyl ketone, propenylallyl ketone, phorone, mesityloxide,

and vinyl benzyl ketone; sulfones such as methyl vinyl sulfone, butylpropenyl sulfone and benzyl propenyl sulione; and amides such asacrylamide, methacrylamide and crotonamide. Unsaturated organiccompounds containing not more than about 20 carbon atoms are of themolecular size preferred for employment inthe process of the invention.

The class of unsaturated compounds preferred for employment in theprocess of the invention are substituted aliphaticmonooleflns in whichthe substituent is attached to a. doubly-bound carbon atom and is ameta-directing group, the attaching atom of whichiis unsaturated. Thecompounds of, this class are typified by acrylonitrile, methylarcrylate, sodium acrylate, methyl vinyl ketone and l-nitro-l-propene.

In general, any hydroperoxide which is stable at temperatures aboveabout C. is suitable for employment in the process of the invention, butthe employment of hydrocarbon peroxides (compounds of the formulaR-O-O-H in which R. is a hydrocarbon radical) or their halogen-analogscontaining one or more chlorine or bromine atoms is preferred. 7

Illustrative examples of hydroperoxides which are suitable foremployment in the process of the consists of the tertiary-hydrocarbonperoxides and their halogen-analogs containing one or more chlorine orbromine atoms. This class includes, for example, such substituted orunsubstituted tertiary alkyl hydroperoxides as teritarybutylhydroperoxide, a,a-dimethylbenzyl hydroperoxide, chlorotertiary-butylhydroperoxide lchloromethyl-l-bromomethylpropyl hydroperoxide as well asl-methylcyclohexyl hydroperoxide.- I

A solvent is not required in the process, but the presence of amutualsolvent, particularly water, is preferred. In general, any solventinert to the reactants under the conditions of the reaction may beemployed. Illustrative examples of suitable solvents include water,alcohols such as isopropyl, butyl and pentyl alcohol; ethers such asdiisopropyl ether, anisol and dioxane; esters such as methyl butyrate,methyl chloroacetate and butyl acetate and liquid amines such asdibutylamine, N-ethyl aniline and pyridine (in the case of the amine,the solvent also functions as the alkaline reacting catalyst).

The addition reaction between the hydroperoxide and the unsaturatedcompound is catalyzed by the presence of an alkaline-reacting material.In general, any substance which is substantially unreactive with thereactants and is miscible with them, or with a solution of them in theparticular solvent employed, can be used as the catalyst. v

The alkali metal hydroxides suchas sodium hydroxide, potassium hydroxideand lithium hydroxide have been found to be particularly suitablecatalysts. Other water-soluble metal hydroxides which are relativelystrong bases such as the hydroxides of the alkaline earth metals,barium, strontium, calcium and magnesium, as well as ammonium hydroxide,may also be employed.

asoaase Suitable organic catalysts include aliphatic amines such asmethyl, ethyl, butyl, amyl, and the like amines; complex-ammonium basessuch as tetramethylammonium hydroxide; and cyclic lanniines' such asptpereline, pyridene, and the The products provided by the presentinvention are polyfunctional compounds exhibiting prop ertiescharacteristic of organic peroxides as well as, respectively, of theacids, nitriles, esters, ketones and the like. For example, methyltertiarybutylperoxy-propionate, produced from a reaction oftertiary-butyl hydroperoxide and methyl acrylate conducted in accordancewith the .process of the. invention, sputters when heated, and whenburned on a filter paper burns with sputtering, thusexhibitingcharacteristic peroxide properties. Sodium'tertiary-butylperoxypropionate is interconverted from acid to salt bythe action of acids and metal hydroxide thus exhibiting characteristicacid properties. Tertiarybutyl 2-cyanoethyl peroxide when employed as acatalyst for the emulsion polymerization of an 80:20methylpentadiene-butadiene mixture produced a polymer having a farhigher Mooney plasticity than other polymersprepared under identicalconditions from peroxides containing no polar. substituent, thusexhibiting not only the characteristic peroxide properties but enhancedproperties due to the presence of the polar group in the molecule. Ingeneral, the compounds provided by the present invention areparticularly valuable in that they provide a means of greatly extendingthe existing knowledge of peroxidic compounds. In addition to theirdirectcommercial value as peroxides having greatly modified solubilitycharacteristics and as peroxidic compounds from which other types ofperoxidic substances can be synthesized (by virtue of the knownconversion procedures applicable to the functional groups the presentcompounds contain in addition to the peroxy group), the compoundsundergo the characteristic peroxidic decomposition, and in so doing,form free radicals of structures heretofore unattainable.

As their structure is relatively complex, names of the compoundsprovided by the present invention do not readily convey their structureto the reader. The compounds can be more clearly visualized as theproducts of an addition reaction, between a hydroperoxide of the definedclass and an unsaturated compound of the defined class, in which a C=CXgroup of the unsaturated compound, where X is a meta-directin group, issaturated by the attachment of a hydrogen atom to the doubly-boundcarbon atom hearing the least hydrogen atoms, and the attachment of aR-O-O-group to the doubly-bound carbon atom bearing the greatest numberof hydrogen atoms.

The reaction involved in the process of the present invention ispreferably conducted in the liquid phase. Substantially any pressure cansuitably be employed, but the employment of atmospheric orsuperatmospheric pressure is preferred. The addition reaction is rapidand the process can be conducted as a batchwise or continuous operation.The temperature at which the process is conducted can be varied overwide limits, in general, any temperature of from about 0 C. to thedecomposition temperature of the hydroperoxide is suitable. Temperatureswithin about ten degrees above or below normal room atoaaee temperatureare particularly easy to'maintain and are productive of good yields.

The proportions in which the reactants are combined may be variedwidely, but as the addition reaction is a mole-to-mole addition, it ispreferable to employ the hydroperoxide and the unsaturated compound insubstantially equimolar portions, unless it is desirable to conserve adifficultly obtainable hydroperoxide or unsaturated compound byemploying an excess of the other. In any case, suflicientalkaline-reacting material should be. employed to render the reactionmixture alkaline throughout the mixing of the reactants, and as theaddition-reaction occurs between the hydroperoxide and the unsaturatedcompound, the alkaline-reacting compound should be present inless thanthe amount required to convert all of the hydroperoxide to the salt. Theemployment of an amount of an alkaline-reacting material substantiallyequivalent to from 1 to 5% by weight of potassium hydroxide (based onthe weightof hydroperoxide, unsaturated compound and/or solvents). ispreferred and the alkaline-reacting material should be added so thatsuch an amount is maintained in the reaction mixture throughout thereaction.

. The following examples illustrate in detail the application of theprocess of the invention to the production of particular compounds. As'

numerous variations in reactants and reaction conditions are withinthescope of the invention, the invention is notto be construed aslimited to the particular materials and reaction conditions recited inthe application.

Erample' I.Preparation of a cyano-substztuted 1 hydrocarbon peroxide 1Tertiary-butyl v2-cyanoetl'iyl peroxide is -prepared in accordancewiththe process of the invention byz p (A) Slowly adding,over a period of 30minutes, 13.3 cc. (0.2 mole) ofacrylonitrile toa mixture of 96.6 cc. ofan aqueous 80% solution of tertiarybutyl hydroperoxide with 6 cc. of anaqueous 40% solution of potassium hydroxide, while maintaining the.reactants, with stirring, at a temperature of from 30? C..to 35 C.

(B) Slowly adding, over a period of 30 minutes, 13.3 cc. (0.2 mole) ofacrylonitrile to a mixture of 96.6 cc. of an aqueous 80% solution oftertiary-] butyl hydroperoxide with 9 cc. of an aqueous 30% solution oftetramethylammonium hydroxide, while maintaining the reactants,'withstirring, at a temperature of from C. to C.

The substituted peroxide is isolated by removing, by an extractionand/or fractional distillationaof the reaction mixture, the unreactedhydroperoxide, nitrile and alkaline catalyst. -uTertiary-butylZ-cyanoethyl peroxide has the formula, a

A" sample of tertiary-butyl 2-cyanoethyl peroxide was prepared by thereaction described as (A) above. The reactants were stirred at atemperature of "C. to C. for onehour after the addition of the nitrile.The substituted peroxide was isolated by extracting from it, with water,the unreacted hydroperoxide and nitrile. The peroxide was a, water-whiteliquid,

I agony 11 1.4142 having a characteristic peroxidic odor.

Found Per cent (J Per cent H "1--..-- Per cent N Per cent M. W.(aye-benzene... Eq. wt. (as oxid. agent toward KI) san . gr Ps lllbamm Anon-tertiary hydroperoxide may be employed in the process of theinvention in an entirely analogous manner, for example, ethyl2-cyanoethyl peroxide is prepared by slowly adding 13.3 cc. (0.2 mole)of acrylonitrile to a mixture of 38 cc. of an aqueous 50% solution ofethyl hydroperoxide containing 1 cc. of an aqueous solution of potassiumhydroxide, while maintaining the mixed reactants, with stirring, at atemperature of from 20 C. to 25 C.

The substituted peroxide is isolated by removing, by an extractionand/or fractional distillation of the reaction mixture, the unreactedhydroperoxide, nitrile and alkaline catalyst.

Ethyl Z-cyanoethyl peroxide has the formula,

and is a polyfunctional compound which undergoes reactionscharacteristic of the organic peroxides as well as of the nitriles.

Example II.Preparation of an esterified carbowl-substituted hydrocarbonperoxide Methyl 3-tertiary-butylperoxypropionate is prepared inaccordance with the process of the invention by slowly mixing 12.3 grams(0.143 mole) of methyl acrylate with cc. of an aqueous 80% solution (0.4mole) of tertiary-butyl hydroperoxideand 7 cc. of a 40% aqueous solutionof potassium hydroxide so that the reaction mixture remains alkaline andwhile maintaining the mixed reactants, with stirring, at a temperatureof from 30 C. to 35 C. i

The substituted peroxide is isolated by, removing, by an extractionand/or a fractional distilla tion of the reaction mixture, the unreactedhydroperoxide, ester and alkaline catalyst.

Methyl 3-tertiary-butylperoxypropionate has the formula,

on.- -=o-o-cmcrnooocm A sample of methyl 3-tertiary-butylperoxypro-.pionate was prepared by the described reaction process. The mixing ofthe reactants was started by adding the ester to the hydroperoxidecontainhaving the characteristic peroxidic odor. An analysis of theperoxide, and a demonstration that it was free of unsaturation (nobromine was adsorbed by the peroxide when bromine. was passed into asolution of the peroxide in carbon 1| tetrachloride), revealed thefollowing composition Theory 7 I and indicated the peroxide to be of theabove formula,

Found Theory htaloxldll nt 00.2 ass sac 1 2: 023? was mm 56.4: 60.6 M. 5Per cent H 0.8, 0.8 9.05 M01. wt. (cryo-benwne) 173 170 1 III-aceticacid method.

Example [IL-Preparation of an owl-substituted hydrocarbon peroxidel-methyl-l-chloromethylpropyl 2 acetylethyl peroxide is prepared inaccordance with the process of the present invention by slowly mixing 21grams (0.3 mole) of methyl vinyl ketone with 89 cc. of a 50% aqueoussolution (0.3 mole) of 1- methyl-l-chloromethylpropyl hydroperoxldecontaining 1 cc. of a 40% aqueous solution of potas-- and is apolyfunctional compound which undergoes reactions characteristic of theorganic peroxide as well as the reaction of the ketones.

Example IV.Rreparation of a carbozwl-aubstttuted hydrocarbon peroxide3-(,-dimethylbenzylperoxy) -propionic acid is prepared in accordancewith the process oi the invention by slowly adding 38.4 cc. of a 50%aqueous solution of sodium acrylate to 38 grams (0.25 mole) of cumylhydroperoxlde (a,-dimethylbenzyl hydroperoxlde) containing 3 cc. of a40% solution of potassium hydroxide in water while maintaining the mixedreactants, with stirring, at

a temper ture of from 20 C. to 25 C.

The su stituted peroxide is isolated by making the reaction just acid tolitmus and removing by extraction and/or a fractional distillation ofthe reaction mixture the unreacted hydroperoxide, acid and salts.

3-(, dimethylbenzylperoxy) propionic acid has the formula,

and is a polyfunctional compound which undergoes reactionscharacteristic of the organic peroxides as well as reactionscharacteristic of the carboxylic acids.

Example V.Preparation of a nitro-substituted hydrocarbon peroxideTertiary amyl 2 nitroisopropyl peroxide is prepared in accordance withthe process or the present invention by slowly adding 17.4 grams (0.2mole) of l-nitro-lpropene to a mixture or 26 cc. of an 80% aqueoussolution (0.2 mole) oi tertiary-amyl hydroperoxlde containing 6 cc. of

a 40% aqueous solution of potassium hydroxide while maintaining themixed reactants, with stirring, at a temperature of from 20 C. to 25 C.

The substituted peroxide is isolated by removing, by an extractionand/or fractional distilla- 8 tion of the reaction mixture, theunreacted hydroperoxide, oleflnic compound and alkaline catalyst.

' Tertiary-amyl 2-nitroisopropyl peroxide has the formula,

cm 0H1 crncnr-c'a-o -o-r'monmoi tn. v and is a polyiunctional compoundwhich undergoes reactions characteristic of the organic peroxide as wellas reactions characteristic of the nitro compounds.

The invention claimed is:

1. Methyl 3-tertiary-butylperoxypropionate.

2. Tertiary-butyl 2-cyanoethyl peroxide.

3. A tertiary-alkyl 2-cyanoalkyl peroxide.

4. An alkyl S-(tertiary-alkvlperoxy) alkanoate.

5. A method of preparing tertiary-butyl 2- cyanoethyl peroxide whichcomprises heating to a temperature between 20 C. and C. an aqueoussolution of acrylonitrile, at least an equivalent amount oftertiary-butyl hydroperoxide, and an amount oi. an alkali metalhydroxide substantially equal to from 1 to5% of the weight of thereactants.

6. A method of preparing methyl 3-tertiarybutylperoxypropionate whichcomprises heating to a temperature between 20 C. and 100 C. an aqueoussolution of methyl acrylate, at least an equivalent amount oftertiary-butyl hydroperoxide,.and an amount of an alkali metal hydroxidesubstantially equal to from 1 to 5% of the weight of the reactants.

' '7. A process for the production of a substituted peroxide, whichcomprises, mixing a hydrocarbon hydroperoxlde with an olefinic compoundcontaining a meta-directing group, the attaching atom of which is anunsaturated atom, attached to, a carbonatom joined by an olefinic doublebond and an alkaline-reacting compound, in the same liquid phase whilemaintaining the mixed reactants alkaline and at a temperatur of from 10c. to the decomposition temperature of the hydroperoxlde.

8. A process for the production of a substituted peroxide, whichcomprises, mixing a hydroperoxide with an oleflnic compound containing ametadirecting group attached to'a carbon atom joined by an olefinicdouble bond and an alkaline-reacting compound, while maintaining themixed reactants alkaline. 1

9. An organic peroxide of the formula xi-o-o-dn cnl-m wherein R1 is atertiary alkyl group, R: is a member selected from the group consistingoi. hydrogen atoms and alkyl radicals and R: is a metadirecting groupselected from the group of radicals consisting of -CN,

o o o alkyl, l on, JL-o-nm B-Iid NO2.

DENHAM HARMAN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,403,709 Dickey et al July 9,1946 FOREIGN PATENTS Number Country Date 116,260 Australia Dec. 24, 1942

9. AN ORGANIC PEROXIDE OF THE FORMULA